A technology of forming a three-dimensional object while hardening powder with a binding solution is known (for example, refer to PTL 1). In this technology, a three-dimensional object is formed by repeating the following operations. First, a slurry containing powder particles, a water-based solvent and a water-soluble polymer is thinly spread in a uniform thickness to form a layer, and a binding solution is discharged onto a desired portion of the layer to bind the powder particles together. As a result, in the layer, only the portion onto which the binding solution is discharged is attached to form a thin plate-like member (hereinafter referred to as “section member”). Thereafter, a layer is further formed on this layer, and a binding solution is discharged to a desired portion thereof. As a result, a new section member is formed even on the portion of the newly-formed layer to which the binding solution is discharged. In this case, since the binding solution discharged on the powder layer penetrates this layer to reach the previously-formed section member, the newly-formed section member is attached to the previously-formed section member. The thin plate-like section members are laminated one by one by repeating these operations, thereby forming a three-dimensional object.
In this technology of forming a three-dimensional object, when three-dimensional shape data of an object to be formed exists, it is possible to directly form a three-dimensional object by binding powder particles, and there is no need to create a mold prior to formation, so that it is possible to quickly and inexpensively form a three-dimensional object. In addition, since the three-dimensional object is formed by laminating the thin plate-like section members one by one, for example, even in the case of a complex object having a complicated internal structure, it is possible to form the three-dimensional object as an integrally-formed structure without dividing the complex object into a plurality of parts.
However, in the related art, there is problem in that, when a layer (upper layer) is laminated on the formed layer (lower layer) by supplying a forming slurry, a water-soluble polymer binding the particles in the lower layer is melted by a water-based solvent contained in the forming slurry, and thus the shape of the lower layer is changed. Therefore, it is not possible to manufacture a three-dimensional structure with sufficient dimensional accuracy.